const config = require('../config');

const PATH = 'chat/completions';
/** 读图较慢，与 ai.js REQUEST_TIMEOUT_IMG_MS 对齐 */
const TIMEOUT_MS = 180000;

/**
 * 将单 URL 或 URL 数组规范为字符串数组（OpenAI 兼容：同一 user 消息里多段 image_url = 多图）
 */
function normalizeImageUrls (imageUrlOrUrls) {
  if (Array.isArray(imageUrlOrUrls)) {
    return imageUrlOrUrls.map((u) => String(u || '').trim()).filter(Boolean);
  }
  const s = String(imageUrlOrUrls || '').trim();
  return s ? [s] : [];
}

function buildUserContent (prompt, imageUrlOrUrls) {
  const urls = normalizeImageUrls(imageUrlOrUrls);
  const content = [{ type: 'text', text: String(prompt || '') }];
  for (const url of urls) {
    content.push({
      type: 'image_url',
      image_url: { url, detail: 'high' },
    });
  }
  return content;
}

function resolveModel (modelOverride) {
  return (
    (modelOverride && String(modelOverride).trim()) ||
    (config.IMG2TEXT_MODEL && String(config.IMG2TEXT_MODEL).trim()) ||
    config.MODEL_NAME ||
    'gpt-4o'
  );
}

/** 截图 ROI（img-center）：默认读 config.IMG_CENTER_MODEL，与 img2text 默认解耦 */
function resolveImgCenterModel (modelOverride) {
  return (
    (modelOverride && String(modelOverride).trim()) ||
    (config.IMG_CENTER_MODEL && String(config.IMG_CENTER_MODEL).trim()) ||
    (config.IMG2TEXT_MODEL && String(config.IMG2TEXT_MODEL).trim()) ||
    config.MODEL_NAME ||
    'gpt-5.4'
  );
}

/**
 * OpenAI 兼容 POST /v1/chat/completions
 * @param {string} prompt
 * @param {string|string[]} imageUrlOrUrls 单张 data URL / https URL，或多张（多附件）
 * @param {string} [modelOverride]
 */
function getBody (prompt, imageUrlOrUrls, modelOverride) {
  const urls = normalizeImageUrls(imageUrlOrUrls);
  if (urls.length === 0) {
    throw new Error('img2text: 至少提供一张图片（字符串 URL 或 URL 数组）');
  }
  const model = resolveModel(modelOverride);
  const content = buildUserContent(prompt, imageUrlOrUrls);
  return {
    model,
    messages: [{ role: 'user', content }],
    // 勿与 max_completion_tokens 同时传：部分聚合网关（如 ChatAnywhere）会报错
    max_tokens: 1024,
    stream: false,
  };
}

function getDoubaoBody (prompt, imageUrlOrUrls, modelOverride) {
  const urls = normalizeImageUrls(imageUrlOrUrls);
  if (urls.length === 0) {
    throw new Error('img2text: 至少提供一张图片');
  }
  const model =
    (modelOverride && String(modelOverride).trim()) || config.DOUBAO_MODEL;
  const content = buildUserContent(prompt, imageUrlOrUrls);
  return {
    model,
    messages: [{ role: 'user', content }],
    max_tokens: 1024,
    stream: false,
  };
}

module.exports = {
  path: PATH,
  getBody,
  getDoubaoBody,
  /** img-center：无 override 时用 config.IMG_CENTER_MODEL（环境变量 IMG_CENTER_MODEL） */
  resolveImgCenterModel,
  timeoutMs: TIMEOUT_MS,
  /** 测试/调试：看 content 结构 */
  buildUserContent,
  normalizeImageUrls,
};